The invention relates to a paper machine of the kind having a continuous inner wire cloth and a continuous outer wire cloth which are passed together around a deflecting component, located within the inner wire cloth, for effecting centrifugal extraction of water out of the outer wire cloth, said machine also having a water extraction box located within the inner wire cloth in front of the deflecting component, and a breast box, an upper lip of which lies adjacent the outer wire cloth in the vicinity of the water extraction box and defines, with a support surface provided by the water extraction box, a preliminary water extraction zone in which water can be extracted through the inner wire cloth into the water extraction box.
In a known paper machine of this kind, for example, U.S. Pat. No. 3,891,500, the inner wire cloth passes over a deflecting roller on a suction box, then over a free section without support and subsequently, together with an outer wire cloth, over a blowing roller on which water is spun out through the outer wire cloth. Above the suction box there is located the curved upper lip of a breast box, the lower lip of which terminates right at the beginning of the suction box. In this way, a preliminary water extraction zone is defined by the upper lip and the suction box. Further, it is known to extract water to either side within the fibrous web-forming zone, as shown in German Patent Specification No. 1,960,884.